Brantly, 33, has been working with Samaritan's Purse in Liberia since October 2013 as part of the charity's post-residency program for doctors, said the group's spokeswoman Melissa Strickland. The organization's website says he had worked as a family practice physician in Fort Worth, Texas.
The highly contagious virus is one of the most deadly diseases in the world. Photos of Brantly working in Liberia show him in white coveralls made of a synthetic material that he wore for hours a day while treating Ebola patients.
Brantly was quoted in a posting on the organization's website earlier this year about efforts to maintain an isolation ward for patients.
"The hospital is taking great effort to be prepared," Brantly said. "In past Ebola outbreaks, many of the casualties have been healthcare workers who contracted the disease through their work caring for infected individuals."
Strickland says that Brantly's wife and children had been living with him in Africa, but they are currently in the U.S.
A woman who identified herself as Brantly's mother answered a U.S. phone listing for him, but said family members are declining comment at this time.
The deadly disease has killed at least 672 in several African countries since the outbreak began earlier this year.